Interpretive Summary: Invasive species are of great concern to U.S. agriculture not only because of the potential damage they cause to native, ornamental, and agricultural plants, but also because of the quarantine and export restrictions that may accompany their presence in this country. This paper chronicles the discovery of a newly introduced insect, the light brown apple moth, into the western U.S., and provides details on its distribution, life history, and morphology. This information will be valuable to local, state, and federal departments of agriculture, extension entomologists, pest managers, and action agencies such APHIS, whose responsibilities include the exclusion of foreign pests.

Technical Abstract:
The light brown apple moth (LBAM), Epiphyas postvittana (Walker), is a highly polyphagous species that is an important pest of apple and citrus in many parts of the world, primarily Australia and New Zealand. The potential threat of LBAM to North American agriculture was recognized formally in 1957 by the inclusion of this species in the pest alert series “Insects Not Known to Occur in the U.S” of the Cooperative Economic Insect Report. Although LBAM was excluded from a list of the top 100 most dangerous exotic pests of concern to the United States in 1973, most regulatory entomologists continued to cite this species in risk assessments to the present. LBAM was first discovered in Berkeley, California (Alameda Co.), U.S.A. in 2006. Subsequent trapping efforts in 2007 and 2008 by the California Department of Food and Agriculture and the United States Department of Agriculture revealed its presence in San Francisco, Contra Costa, San Mateo, Santa Cruz, Santa Clara, Marin, Monterey, Napa, Sonoma, Solano, San Luis Obispo, Santa Barbara, and San Benito counties, California. One individual was trapped in Los Angeles County (Sherman Oaks) in June 2007 and another in Ventura County in February 2009. The latter two captures do not fit the criteria of an established population. Previous surveys in California over the past 40 years, for LBAM in particular and for Lepidoptera in general, covering the present known geographical range of LBAM, failed to detect this species. These data suggest that LBAM arrived in California only recently. We provide descriptions, diagnoses, and illustrations to aid in the identification of this newly arrived pest, along with a history of its discovery.